The defence got exposed because the Leafs refused to properly support a breakout.
You look at how Florida broke out of the zone... it's always as a 3-man unit, making short passes. The Leafs were constantly flying the zone, trying to make a stretch pass to be able to outnumber on a dump in. It made them very susceptible to the aggressive forechecks.
Ultimately, you look at who the Leafs have under contract for next year on D, and they're probably 1 D short... Rielly-X, McCabe-Brodie, Giordano-Liljegren, with Timmins as a #7. I'd like to see Schenn stay, as a guy that might bounce in and out of the lineup with Timmins; if you can get somebody that really fits that #2 role.